Origin and Habitat: Western Texas, southeastern New Mexico, and northern Mexico.Type locality: About El Paso, Texas.Altitude: 1200-1600 metres above sea level.Habitat: It grows on arid areas in igneous and sedimentary soils, that usually are more arid than is typical for the related var. cylindricus. It is often found growing along with Coryphantha vivipara.

Description:Echinocereus viridiflorus var. chloranthus is somewhat like Echinocereus viridiflorus, having similar small flowers. It is usually more elongated, with a bristly appearance, horizontal colour banding, longer and curved lower central spines and with the flowers appearing lower down on the plant, generally below the middle. In habitat this plant integrates with Echinocereus viridiflorus var. cylindricus (fewer central spines) and Echinocereus viridiflorus var. russanthus (more central spines) and it is very difficult to distinguishes it from its relatives, generating more confusion among cactus fanciers and grower about it than about any other Echinocereus species. Moreover at a first glance, if not in flower, it may be confused with Echinocereus dasyacanthus. Habit: It is usually simple or branching, but older plants may exhibit limited branching with as many as 10 or more branches.Stem: Cylindrical, erect, pale green, 7-15(-25) cm long, 5 to 8 cm. in diameter.Ribs: About (10-)11-16(-18), often nearly hidden by the densely set spines, well defined, undulate, and tuberculate, at the areoles with shallow furrows between the ribs and the tubercles.Areoles: Nearly circular, or elliptic to oblong and 3-4 mm long, and 3-6 mm apart on the ribs. Only areoles near the stem apex have copious short white wool. Floriferous areoles remains as persistent conspicuous tuft of wool even after the flower or fruit has fallen. Central spines: (2-)3-4(-6), not angled, straight, 6-20 mm long, when they number two or three, they are positioned in a single vertical row otherwise, they spread in all directions, usually reddish (Rarely cream or yellowish), the lower one often curved, much more elongated than the others, usually white, somewhat translucent, although often with a reddish tip, and up to 20-30 mm long. In juvenile plants the central spines are more slender than in adults and may be absent or present. Radial spines: Several (15-23 or more), tightly appressed, evenly radiating around the areoles or slightly spreading, 12-14 mm long, the upper 4-6 of them often shorter and weaker, never hairy, quite variable in colour even in different areoles on the same plant, ashy white, cream, grey, reddish, or reddish black, or even variegated often with darker distal portions or tips and forming horizontal bands around the stem. In juvenile plants the radial spines are short, pectinate, and appressed, except in turgid seedlings, where the radials may be spreading. All the spines has a bulbous base but usually covered, until they are very old, by the wool of the areoles.Flowers: Produced on lateral midstems, but sometime lower, funnelform, not opening widely, 20-34 mm long, dark green, yellowish green, bronze-green, brown or dark chocolate-brown, 2 cm. long. Usually unscented. Ovary with white wool and white spines about 6-12 mm long. Inner perianth segments 2,5-5 mm wide, not broadening throughout their length brownish-green or rusty and greener toward the center, often with dark green midlines with the margins lighter green and suffused with brown, tips acute-apiculate, rounded, or even emarginate. Outer perianth segments often with brownish midlines and margins olive-yellow. Filaments pale yellow or greenish. Anthers cream coloured or yellow. Stile greenish, 1,2-2 cm long. Stigma lobes 8-10 dark green. Blooming season: Spring for 15-30 days. ( in habitat from March through May). Individual plants or stems may produce more than 30 flowers at a time.Fruits: Small, nearly globular, 5 to 17 mm long, green (or dull purplish red), indehiscent, covered with small bristly spines, that easily fall away, leaving a glistening fruit wall.Seeds: 1-1,3 mm long and broad, black, dull, papillate (pitted), the hilum nearly basal, round.

Subspecies, varieties, forms and cultivars of plants belonging to the Echinocereus viridiflorus/russanthus complex

Echinocereus viridiflorusEngelm. in Wisliz.: ssp. viridiflorus(Typical form) With small stems and relatively pure yellow flowers, extends from central New Mexico and the Texas Panhandle to South Dakota.

Echinocereus viridiflorus subs. chloranthus(Engelm.) N.P.Taylor: has 10-18 ribs, 5 or more central spines, giving the plants a bristly appearance, it is often considered a separate species (Echinocereus chloranthus). Distribution: W. Texas, S.E. New Mexico, and N. Mexico.

Echinocereus viridiflorus subs. davisii(Houghton) N.P.Taylor: In the broad senseEchinocereus viridiflorus may prove paraphyletic with respect to Echinocereus davisii, but they are phenologically isolated, with Echinocereus davisii flowering earlier and thus appearing reproductively isolated in the wild.

Echinocereus viridiflorus var. robustiorKuenzler: It is a more robust form but not sufficiently differentiated and considered merely a local variant of Echinocereus viridiflorus var viridiflorus. Distribution New Mexico.

Notes: Echinocereus chloranthus is part of the Echinocereus viridiflorus complex that comprises a large number of infraspecific taxa, differing in various combinations of flower color, spine color, number and thickness of central spines, and other characters, including floral scent. Wherever such taxa are sympatric they intergrade; all are freely interfertile in the greenhouse.

Cultivation and Propagation: In culture it is without problems and regularly shows its small greenish flowers if we provide an adequate winter rest period. They are re small plants with scented flowers that are better close to nose level. Displaying your cacti on shelves has the added benefit of keeping them off the ground and away from potential rodent or snail damage. Soil: Use mineral well-permeable substratum with little organic matter (peat, humus). Repotting: Repotting every 2-3 years. It will need a pot with sufficient depth to allow the tap root. As it is especially prone to rot under-pot in a smaller container filled with very porous compost. Use pot with good drainage.Watering: Water sparingly from March till October, and keep perfectly dry in winter, at temperatures from 5 to 15 degrees centigrade. In the rest period no high atmospheric humidity!!Care must be taken with watering as they tends to become swollen and untidy in growth habit if given too much water and shade.Exposition: Outside bright sun, filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Subject to sunburn if exposed to direct sun for too long. Tends to bronze in strong light, which encourages flowering and heavy spine production. Hardiness: Keep drier and cool in winter. Very cold resistant hardy to -10° C or less for short periods of time. Fertilization: During the growing season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for: - Red spiders: Sensitive to red spider mite. Overhead watering is helpful in controlling mites. - Mealy bugs: Occasionally mealy bugs they develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects. - Scales: Scales are rarely a problem. - Rot: Rot it is only a minor problem with cacti if the plants are watered and “aired” correctly. If they are not, fungicides won't help all that much.Propagation: Seeds or cutting (if available). Seeds germinate in 7-14 days at 21-27° C in spring, remove the glass cover gradually as the plants develops and keep ventilated, no full sun for young plants! The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots.